The present invention relates to targeting a stain on a fabric with a bleach catalyst. The invention also relates to a detergent composition comprising a targeted bleach catalyst and to a process for bleaching stains present on a fabric.
EP9803438 (Unilever) discloses the use of a bleaching enzyme, which is capable of generating a bleaching chemical and has a high binding affinity, recognition, for stains present on fabrics. The enzyme comprises an enzyme part capable of generating a bleaching chemical, coupled to a reagent having a high binding affinity, recognition, for stains present on fabrics. An advantage provided by EP9803438 is that the stained part of the garment, typically the minority, is exposed to higher levels of bleach than the unstained part of the garment, typically the majority.
The use of bleaching catalysts for bleaching stains has been developed over recent years. The resent discovery that some catalysts are capable of bleaching effectively with air has recently become the focus of some interest, for example, GB applications: 9906474.3; 9907714.1; and 9907713.3 (all Unilever). Many of the bleaching catalysts are relatively complex molecules that are not cheap to produce. As with any cleaning product a more economical use of active components and effective stain bleaching profile is sought.
It is an object of the present invention to provide a more effective bleaching catalyst over the teachings of GB applications: 9906474.3; 9907714.1; and 9907713.3 (all Unilever) and other bleach catalysts per se as found in, for example, GB 9027415.0, DE 19755493, EP 999050, WO-A-9534628, EP-A-458379, EP 0909809, U.S. Pat. No. 4,728,455, WO-A-98/39098, WO-A-98/39406 and WO 9748787.
The present invention provides a means for bleaching stains on a fabric using a targeted bleach catalyst.
The bleach catalyst is bound to an antibody, the antibody having a selective affinity, recognition, for at least one type of stain. In this manner, a targeted bleach catalyst is held close to the stain thus enhancing bleaching activity over that of non-targeted bleach molecules. The bleach catalyst is either covalently bound to the antibody or bound by antibody recognition of the bleach catalyst. Alternatively, the bleach catalyst is bound to an enzyme; the enzyme is then bound to an antibody that recognises at least one type of stain.
According to a present invention there is provided a bleaching composition comprising an organic substance which forms a complex with a transition metal, the complex catalysing bleaching of a substrate by a precursor selected from atmospheric oxygen, a peroxyl species and a peroxyl species precursor, characterised in that the bleaching composition comprises a recognising portion having a high binding affinity for stains present on a fabric or fabric, wherein in an aqueous solution the organic substance and the recognising portion bind together.
The composition of the present invention may be used in an aqueous or non-aqueous medium, for example, dry cleaning fluids or liquid carbon dioxide.
The present invention extends to a method of bleaching a substrate comprising applying to the substrate, in an aqueous medium, the bleaching composition according to the present invention.
The present invention extends to a commercial package comprising the bleaching composition according to the present invention together with instructions for its use.
The bleach catalysts of the present invention may be a peroxyl species bleach catalyst and/or an oxygen bleach catalyst.
One skilled in the art will appreciate that not all peroxyl activating catalysts are capable of functioning as an oxygen activation catalyst. However, the converse is likely not true. There is no evidence to indicate that any oxygen activation catalyst will not function as peroxyl activating catalyst. In this regard, all oxygen activation catalysts disclosed herein may be used as a peroxyl activating catalyst. Catalysts of the present invention may be incorporated into a composition together with a peroxyl species or source thereof. For a discussion of acceptable ranges of a peroxyl species or source thereof and other adjuvants that may be present the reader is directed to U.S. Pat. No. 6,022,490, the contents of which are incorporated by reference.
When bleaching with atmospheric oxygen or air, it will be appreciated that small amounts peroxyl species may be adventitiously present in a bleaching composition. Nevertheless, the bleaching composition is substantially devoid of peroxygen bleach or a peroxy-based or -a generating bleach systems. By xe2x80x9csubstantially devoid of peroxygen bleach or peroxy-based or -generating bleach systemsxe2x80x9d it is meant that the composition contains less than 2%, preferably less than 1%, by molar weight on an oxygen basis, of peroxygen bleach or peroxy-based or -generating bleach system. Preferably, however, the composition will be wholly devoid of peroxygen bleach or peroxy-based or -generating bleach systems when used for bleaching with air.
Thus, at least 10%, preferably at least 50% and optimally at least 90% of any bleaching of the substrate is effected by oxygen sourced from the air.
In the instance that a peroxyl species bleach catalyst is used a peroxyl species may be present in the bleaching composition, or the peroxyl species may be generated in situ. Alternatively, a precursor for a peroxyl species is present in the bleaching composition, for example the glucose oxidase enzyme.
A bleaching composition comprising an oxygen bleach catalyst may be substantially devoid of peroxyl species or precursor thereof. In such a bleaching composition oxygen is the primary source of bleaching species. In order to avoid an overly pedantic construction, an oxygen bleach catalyst together with oxygen should not construed as a peroxyl species precursor as used in this context. Nevertheless, the last statement should not be taken as a binding theory; it is possible that a peroxyl species may be generated from an oxygen bleach catalyst together with oxygen. The targeting of the bleach catalyst is postulated to provide an increase in performance in applications by localising its activity at a desired site. It is likely that benefits of the present invention will include:
(1) decreased non specific interaction of the bleach catalyst with laundry components in the bulk phase;
(2) decreased dosage of a potentially expensive ingredient, i.e. the bleach catalyst;
(3) use of the bleach catalyst only when and where required, i.e., on stain therefore less transition metal will remain on the cloth; and
(4) reduced dye/fabric damage.
A reduction the amount of bleach catalyst per unit dose required over non-targeted bleach catalysts may provide a scenario in which a transition metal complex per se is not provided in the bleach composition. The transition metal complex may be formed in situ during a wash. The transition metal is provided either by the wash liquor or a stain. In many regions of the world the water supply contains substantial levels of transition metal ions, in particular iron. In addition, a stain often contains transition metal ions, in particular iron. Therefore, by having only the organic substance (ligand), i.e., non-complexed, bound to the recognising portion the organic substance becomes activated by xe2x80x98findingxe2x80x99 the metal ions in the wash water, the stain or added metal salt.
A unit dose as used herein is a particular amount of the bleaching composition used for a type of wash. The unit dose may be in the form of a defined volume of liquid, powder, granules or tablet.